Mr. Bumbledrop from Torchy the Battery Boy was the first puppet in a Gerry Anderson
production to have different facial expressions, however, the difference was only a bit of
paint to add "worry lines".
More elaborate facial expressions came with Stingray (although blinker heads have been used along with normal heads in Fireball XL5).
The usual collection of heads for any character include a normal or neutral expression, a smiling expression, a frowning expression, and a neutral face that can blink.
The facial expressions changed by replacing the head of the puppet, which means that the expressions cannot change without a hard-cut to a new shot.
With modern animatronic technology, such as used in Team America World Police, not only are the expressions of a puppet character more varied, but also they can change on-screen, looking more natural and realistic.